Swiftfox was a web browser based on Mozilla Firefox. It was available for Linux platforms and distributed by Jason Halme. Swiftfox was a set of builds of Firefox optimized for different Intel and AMD microprocessors. Swiftfox was freely downloadable with open source code and proprietary binaries. Firefox extensions and plugins were compatible with Swiftfox, with notable exceptions. The name Swiftfox comes from the animal swift fox. Swiftfox differs from Firefox by a limited number of changes, and builds for different processors. Swiftfox was discontinued at some point prior to April 2017, and the project homepage now redirects to the creator's private Twitter account.

The Swiftfox build is optimized using the following methods:

Binary code optimization

Increased security

Simplify

Changed default preference values

No definitive benchmarking has been reported, but a quicker startup time and a 1.7% webpage rendering speedup has been reported on version 1.5.0.6. There are no benchmarks for the different processors builds.

Swiftfox is bundled with the following freely available Firefox plugins and extensions: